In recent years, with the progress in miniaturization of semiconductor devices, problems in photolithography processes that are pattern drawing processes used in processes of manufacturing semiconductor devices are getting more and more significant. As the pattern width becomes smaller, resolving power resulting from pattern transfer using light is becoming insufficient, and nano-imprint technologies are increasingly used in place of pattern transfer using light.
The imprint technologies are technologies of pressing an imprint mask with a pattern formed thereon onto an imprint material applied to a wafer substrate, and hardening the imprint material, whereby the pattern formed on the imprint mask is transferred onto the wafer substrate to form the pattern thereon.
In manufacturing of semiconductor devices using the photolithography technologies and the imprint technologies, a pattern that is the same as or different from a pattern preformed on a wafer substrate needs to be formed on the preformed pattern. In the series of pattern forming processes, high-accuracy registration between the patterns is required.
Patterns formed on a photolithographic mask and an imprint mask, however, each have deviation from the design position, and the deviations from the design positions need to be corrected in order to meet the requirement of high-accuracy registration.
To meet such a requirement, in a photolithography process, positional deviation of a pattern formed on a mask substrate can typically be resolved up to a one-dimensional component thereof corresponding to enlargement/reduction or up to two or three components thereof by a lens optical system for projection in a reduced size on the wafer substrate. Furthermore, in an imprint process, correction of a one-dimensional component corresponding to reduction can be carried out by pressing an end face of an imprint mask. With both of photolithography and imprint, however, there are positional deviations of higher dimension that cannot be completely corrected by the correction method mentioned above.
To correct such positional deviation of higher dimension, a technology of irradiating a mask substrate with laser light to form a heterogeneous layer that expands in volume more greatly than a peripheral area thereof in the mask substrate so that the mask substrate itself is changed in shape and the positional deviation is thus corrected, for example, is starting to be used. It is expected that correction of positional deviation of higher dimension will be carried out by forming a heterogeneous layer that expands greatly in a specific direction depending on a laser light irradiation condition in a mask substrate, for example.
Since, however, volume expansion is dominant for a heterogeneous layer in a mask substrate formed as a result of irradiation with laser light, irradiation of a pattern with laser light to correct positional deviation of higher dimension tends to result in enlargement of the pattern area drawn on a photolithographic mask or an imprint mask. Furthermore, there are problems that positional deviation of high dimension in a pattern area cannot be corrected and that the size of the entire pattern area cannot be adjusted to a desired size if the effect of reducing a pattern as a result of enlarging/reducing a photolithographic mask by an optical system or pressing a side face of an imprint mask as described above is unlikely.